The present invention relates generally to agricultural machinery and more particularly to an improved pressure roller for use in a harvesting machine. Advantageously, the roller is in the form of a hollow cylinder having a plurality of mutually spaced support plates, wherein stub hubs serve as rotational axes for the roller and are fixed to the ends of the hollow cylinder.
Pressure rollers are used in round balers, although they are also referred to as compression rollers in forage harvesters or sugar cane harvesting machines, as well as corn cracker rollers in forage harvesters and other comparable applications. Balers are also used for compacting and wrapping refuse or recyclable materials. Hence, the terms xe2x80x9cagricultural machineryxe2x80x9d and xe2x80x9cbalerxe2x80x9d should be taken as encompassing all uses for such equipment. However, as one example of use, the device will be explained hereinafter as it is used in a round-baler.
It is known from the product catalogue issued by the company CLAAS KGaA .xe2x80x9cRound Balers Rollant 66 46 46 ROTO CUTxe2x80x9d bearing the printing date August 1998 at page 16, to stabilize a pressure roller in the form of a hollow cylinder having a plurality of mutually spaced support plates within the hollow cylinder, with all of these support plates attached at their peripheries in non-rotatory manner to the roller casing by means of welded joints. Transfer of torque from the roller hubs to the roller casing and flexural stresses cause strain between the roller casing and the peripheral boundaries of the support plates, thereby destroying the welded connections and resulting in the support plates breaking off, rendering the rollers unusable. Compared to the previously satisfactory, conventionally reinforced rollers, damage of this nature occurs more often when the rollers are subjected to particularly high loads such as those produced by the increased baling pressures occurring in the newer, high performance round balers. High loads effective axially and as quasi point-like sources at one position of a roller, cause the roller to become deformed in that it tends to bend or to bow. If this roller is then loaded during operation and while rotating, the connections between the outer roller casing and the inner support plates are subjected to changing loads which may eventually lead to the occurrence of brittle fractures in these connections. Once the connection to the roller casing has been broken, the support plates may lay flat and start to move around. The rollers will then bulge and break. The consequences of such roller breakages are high repair costs and interruptions in the work pattern of the machine.
It is an object of the invention to overcome one or more of the deficiencies described above.
Another object is to develop the rollers of the type mentioned above in such a way as to make them sturdier while still retaining their light construction and ease of installation.
In accordance with the present invention, there is provided a roller for harvesting machines, wherein said roller is in the form of a hollow cylinder having an exterior wall and opposite ends, a plurality of mutually spaced inner support plates engaged with an inner surface of the wall, a stub shaft at each end of the cylinder and fixed to the respective end of the cylinder, the stub shafts serving as rotational axis for the roller, and means for preventing lateral displacement of the plurality of inner support plates and including at least one axle section at the rotational axis of the roller.
Preferably, a plurality of the innermost support plates are connected together by at least one axle section, thereby preventing lateral displacement thereof. The axle section relieves the lateral flexural forces exerted upon the individual support plates and distributes said forces over the adjacent support plates that are also connected to the axle section. The peak loads upon the individual support plates are reduced due to the distribution of the load achieved by this form of support. In addition, the micro-movements of the support plates caused by the changing loads are reduced, thereby decreasing the likelihood of brittle fractures.
It can also be advantageous for a plurality of the inner support plates to not be connected to the roller casing in a non-rotational manner. As a result, the micro-movements of the support plates relative to the roller casing, that occur even when the support plates are interconnected by an axle section, will not be prevented by a welded joint, but rather, such movements will be permitted. Since movement is now possible at the points of connection, which are otherwise usually welded, peak loads and brittle fractures at these points can now be avoided. On the other hand, due to their tight fit, the support plates can still absorb point-like loads from the roller casing via their peripheries, the axle section and the other support plates connected to the axle section, thereby distributing these loads over a large area of the roller casing. Even though the support plates are not connected to the roller casing in a non-rotational manner, they still cannot lie flat and move around because they are prevented from so doing by virtue of their rigid connection to the axle section. Since it is the innermost support plates in particular that are subjected to the highest bending moments, it is these which should not be connected to the roller casing in a non-rotational manner. Advantageously however, the outer support discs are connected to the roller casing so as to be able to convey the drive power from the stub hub to the roller casing while preventing axial displacement of the innermost support plates and axle sections.
The inner axle sections are prevented from axial displacement by virtue of the external stub hubs enclosing one or more of the axle sections connecting the support plates together in a co-axial and approximately non-spaced manner.
The outer stub hubs are connected to the roller casing via support plates in a non-rotational manner. The appertaining stub hubs form outwardly extending rotational axes to provide a connection for a drive and mounting means. In this manner, the stub hubs can be economically installed and centralized using only a small number of parts. Only a few assembly components are needed and the support for the stub hubs provided by the support plates permits the drive power to be fed to the roller casing just as the loads effective on the roller casing are passed to the mounting arrangement for the roller.